Python笔记-005- 列表简介

1.3.1 列表是什么

bicycles= ['James','Paul','Wade',' Anthony']
print(bicycles)

这个跟C的数组相似第一位为0。

bicycles= ['James','Paul','Wade',' Anthony']
print(bicycles[0])    # 0:James 1:Paul 2:Wade  3: Anthony

这样就是输出第一个数字的元素，James

注：介绍一种比较特殊的语法,通过索引指定为-1,可以让Python返回最后一个列表元素:

bicycles= ['James','Paul','Wade',' Anthony']
print(bicycles[-1])  # 0:James 1:Paul 2:Wade  3: Anthony

这样子方便在于我们不知道列表长度的情况下直接访问最后的元素，也适用于其他负数索引。

有了索引我们可以使用列表中的各个值

bicycles= ['James','Paul','Wade',' Anthony']
message="My favorite NBA star is "+bicycles[0]+"."
print(message)

动手试一试环节
3-1 姓名: 将一些朋友的姓名存储在一个列表中,并将其命名为 names 。
依次访问该列表中的每个元素,从而将每个朋友的姓名都打印出来。

bicycles= ['Ludan','Aya','Feiji','Dang']
print(bicycles[0])
print(bicycles[1])
print(bicycles[2])
print(bicycles[3])

3-2 问候语： 继续使用练习3-1中的列表， 但不打印每个朋友的姓名， 而为每人打印一条消息。 每条消息都包含相同的问候语， 但抬头为相应朋友的姓名

bicycles= ['Ludan','Aya','Feiji','Dang']
print(bicycles[0]+' How are you?')
print(bicycles[1]+' How old are you?')
print(bicycles[2]+' How old old are you?')
print(bicycles[3]+' How old old old are you?')

1.3.2 修改，增加和删除元素
上面的列表式静态的，很显然不实用，如果我们想要弄成动态的，应该怎么处理呢？
（1）修改索引元素

bicycles= ['James','Paul','Wade',' Anthony']
message="My favorite NBA star is "+bicycles[0]+"."
print(bicycles)
print(message)
bicycles[0] = 'Lebron_James'
message="My favorite NBA star is "+bicycles[0]+"."
print(bicycles)
print(message)

（2）在列表末尾添加元素

bicycles= ['James','Paul','Wade',' Anthony']
bicycles.append('Messi')
print(bicycles)

记：append()函数的存在让动态创建列表易如反掌。
我们可以先建立一个空列表
比如下面代码：

nbastar= []
nbastar.append('James')
nbastar.append('Messi')
nbastar.append('Wade')
nbastar.append('Me')

print(nbastar)

（3）在列表中添加元素

nbastar= []
nbastar.append('James')
nbastar.append('Messi')
nbastar.append('Wade')
nbastar.append('Me')
print(nbastar)
nbastar.insert(0,'Lebron')
nbastar.insert(3,'Paul')
print(nbastar)

（4）在列表中删除元素
既然有添加元素，那么就一定会有删除元素的函数，这个函数是什么？
方法1：使用del语句删除元素

bicycles= ['James','Paul','Wade',' Anthony']
print(bicycles)
del bicycles[0]
print(bicycles)

方法2:使用方法pop()删除元素

bicycles= ['James','Paul','Wade',' Anthony']
print(bicycles)

popped_bicycles=bicycles.pop()
print(bicycles)
print(popped_bicycles)

pop()是删除列表末尾的元素，并且能让你使用它的值。
这个应该应用在哪个场景多一点呢？
假如列表中是按年龄从小到大排序的，那么就可以使用pop()打印出年龄最大的人
别忘了的，当你使用pop()的时候，元素就没在列表中了~！

注：del()跟pop()应该怎么区分好呢？
如果你要从列表中删除一个元素，并且不再使用它的话，那么选择 del();
如果你想要删除元素后还想继续使用它的话，那么选择pop()

（5）根据值删除元素
不知道元素在列表中的那里，但是只要你知道你要删除的值是什么，就可以删除。

bicycles= ['James','Paul','Wade','Anthony']
print(bicycles)
bicycles.remove('Anthony')
print(bicycles)

但是看到这里肯定会有一个疑问：
如果我的列表里面存了很多个一样的数值，我刚好要删除它，是一次性删除？还是只删除一个？
答案是：只删除第一个指定的值，如果删除的值可能在列表中出现多次，就需要用循环判断是否删除了所有的这样的值。接下去学习 我们会接触得到的~~

动手练一练
3-4 如果你可以邀请任何一个人一起共进晚餐，你会邀请哪些人，列一个列表，其中包含至少3个你想要邀请的人，然后使用这个列表打印信息，邀请这些人来共进晚餐

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.')

3-5修改嘉宾
你刚得知有位嘉宾无法赴约，因此需要邀请另外一位嘉宾。
（1）在3-4基础上，在程序末尾添加一个print语句，指出哪位不能赴约

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.')
popped_dinnerpeople=dinnerpeople.pop()
print(dinnerpeople)
print(popped_dinnerpeople+',See you next time.')

（2）修改嘉宾名单，将无法赴约的嘉宾替换为新邀请的嘉宾姓名

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.')
popped_dinnerpeople=dinnerpeople.pop()
print(dinnerpeople)
print(popped_dinnerpeople+',See you next time.')
dinnerpeople.append('Messi')
print(dinnerpeople)
print('Hello '+dinnerpeople[2]+',I am glad you could have dinner with me.')

（3）再次打印一系列消息，向名单中的每位嘉宾发出邀请

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.\n')
popped_dinnerpeople=dinnerpeople.pop()
print(dinnerpeople)
print(popped_dinnerpeople+',See you next time.')
dinnerpeople.append('Messi')
print('Hello '+dinnerpeople[2]+',I am glad you could have dinner with me.\n')
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.')

3.6添加嘉宾
你刚找到一个更大的餐桌，可以容纳更多的嘉宾 。请想想你还想邀请哪三位嘉宾.
（1） 在3-4或者3-5基础上在程序的末尾添加一条print语句，指出你找到一个更大的餐桌。

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.\n')
print('Everybody,I found a bigger table')

（2）使用 insert()将一位新嘉宾添加到名单开头

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.\n')
print('Everybody,I found a bigger table\n')
dinnerpeople.insert(0,'Wade')
print(dinnerpeople)

（3）使用 insert()将一位新嘉宾添加到名单中

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.\n')
print('Everybody,I found a bigger table\n')
dinnerpeople.insert(0,'Wade')
print(dinnerpeople)
dinnerpeople.insert(2,'Paul')
print(dinnerpeople)

（4）使用 apppend()将一位新嘉宾添加到名单中

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.\n')
print('Everybody,I found a bigger table\n')
dinnerpeople.insert(0,'Wade')
print(dinnerpeople)
dinnerpeople.insert(2,'Paul')
print(dinnerpeople)
dinnerpeople.append('Bosh')
print(dinnerpeople)

（5）向每位嘉宾发出邀请

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma']
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.\n')
print('Everybody,I found a bigger table\n')
dinnerpeople.insert(0,'Wade')
print(dinnerpeople)
dinnerpeople.insert(2,'Paul')
print(dinnerpeople)
dinnerpeople.append('Bosh')
print(dinnerpeople)
print("\n")
print('Hello '+dinnerpeople[0]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[1]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[2]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[3]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[4]+',I hope to have dinner with you together.')
print('Hello '+dinnerpeople[5]+',I hope to have dinner with you together.\n')

3-7 缩减名单
你刚得知新购买的餐桌无法及时送达，因此只能邀请两位嘉宾
（1）以3-6为基础，在程序末尾添加一段代码，打印一条你能邀请两位嘉宾的消息
注：为了简便，为了只是验证想法，我将程序修改为4个元素不用3.6但是思路依然一样。
（2）使用POP不断删减嘉宾，知道只有两位嘉宾为止，每次从名单删除一位，都打印一条消息，让嘉宾知道你很抱歉，无法邀请他来共进晚餐

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma','Wade']
print("Everybody,I'm just can invite two people for dinner")
popped_dinnerpeople=dinnerpeople.pop()
print("Mrs "+popped_dinnerpeople+",I'm sorry I can't invite you")
popped_dinnerpeople=dinnerpeople.pop()
print("Mrs "+popped_dinnerpeople+",I'm sorry I can't invite you")

（3）对于剩下的两位嘉宾，都打印一条消息，指出他依然在受邀人之列。

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma','Wade']
print("Everybody,I'm just can invite two people for dinner")
popped_dinnerpeople=dinnerpeople.pop()
print("Mrs "+popped_dinnerpeople+",I'm sorry I can't invite you")
popped_dinnerpeople=dinnerpeople.pop()
print("Mrs "+popped_dinnerpeople+",I'm sorry I can't invite you\n")

print("Mrs "+dinnerpeople[0]+",I hope to have dinner with you together.")
print("Mrs "+dinnerpeople[1]+",I hope to have dinner with you together.")

（4）使用DEL将最后的两位嘉宾从名单上删除，让名单变成了空的。打印出该名单，合适程序结束的时候名单确实是空的

dinnerpeople=['Lebron James','Li Jiacheng','Jack Ma','Wade']
print("Everybody,I'm just can invite two people for dinner")
popped_dinnerpeople=dinnerpeople.pop()
print("Mrs "+popped_dinnerpeople+",I'm sorry I can't invite you")
popped_dinnerpeople=dinnerpeople.pop()
print("Mrs "+popped_dinnerpeople+",I'm sorry I can't invite you\n")

print("Mrs "+dinnerpeople[0]+",I hope to have dinner with you together.")
print("Mrs "+dinnerpeople[1]+",I hope to have dinner with you together.")
del dinnerpeople[0]  
del dinnerpeople[0]  #因为上一条指令删除之后，列表就变成了一个元素，所以第二个删除的指令是 dinnerpeople[0] 而不是 dinnerpeople[1]

print(dinnerpeople)

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